Bombshell figures released by a pressure group say up to 130,000 migrants from Europe will swamp the UK every 12 months.

The 520,000 surge is larger than the population of Manchester – prompting campaign group MigrationWatch UK to claim their findings show Prime Minister David Cameron’s plan to slash immigration is being thrown off course.

However, its report did reveal that the Government has managed to cut entry by non-EU citizens from 217,000 a year to 140,000.

“The bad news is that migrants from the EU have driven the policy off course”

Sir Andrew Green, Chairman of MigrationWatch UK

Calling for a renegotiation of Britain’s EU membership, Sir Andrew Green, Chairman of MigrationWatch UK said: “The good news is that immigration from outside the EU is coming down.

“The bad news is that migrants from the EU have driven the policy off course. It was crazy to have opened up our labour market and our benefit system to people from countries with a standard of living less than a quarter of our own.”

The dossier says handing out benefits only to migrants who have been here for five years could slash the influx. It claimed that future overall net migration, both from within and outside the EU, will be as much as 200,000 a year.

That would add around four million to the predicted UK population increase in the next 20 years.